Joints in cats. What data exists, and what follows from it
There are far fewer studies in cats than in dogs, and most products are derived from the dog. Which reference amounts we use, why they are less certain, and how to spot a product actually meant for cats.
Cats are under-represented in joint research. That is not an aside but the most important sentence here: most feline amounts are carried over from dogs rather than measured in cats. Anyone selling you the same confidence for cats as for dogs is selling a confidence that does not exist.
The reference amounts we use
- Green-lipped mussel: 25 to 50 mg per kilogram per day. Carried over from dogs; there is little feline data.
- Glucosamine: 20 to 30 mg. Common manufacturer dosing, not a study amount.
- Chondroitin sulfate: 15 to 25 mg. Also common manufacturer dosing.
- Omega-3 (EPA + DHA): 30 to 60 mg. From small animal nutrition, set lower for cats than for dogs.
For a 4 kg cat that comes to 100 to 200 mg of mussel powder, 80 to 120 mg of glucosamine, 60 to 100 mg of chondroitin and 120 to 240 mg of EPA plus DHA a day.
Two of those four rows are convention rather than study findings. We say so, because the difference between "used at this level in studies" and "this is what manufacturers do" is exactly the difference a comparison site ought to make visible.
Why products for cats are often under-dosed
Many joint products come in one size for dogs and cats. The feeding guidance then starts at "up to 10 kg: 1 scoop", and a 4 kg cat gets the same amount as a 9 kg dog. Per kilogram the cat is then at double. It happens the other way too: a chew sized for a 30 kg dog cannot sensibly be divided down for a cat.
A product genuinely meant for cats has its own weight bands below 10 kg, a form a cat will actually eat, and amounts per serving stated in milligrams.
With cats, acceptance is half the job
The best-dosed powder is worth nothing if it stays in the bowl. What helps in practice: start very small and build up over one to two weeks, mix the powder into wet food rather than sprinkling it on top, and give oil separately rather than stirring it into dry food, where it can go off.
What belongs with a vet first
If a cat jumps less, grooms differently, or changes its behaviour, the cause is a question for a vet and not for a supplement. Supplements are not a medicine. They can support everyday life, and no more than that.